// 求返回字符串字节数
let a = 'a';
    b = '中';
    c = 'Hello world';
// Blob 是什么？
// 文件 -> Blob -> 二进制
const byteSize = str => new Blob([str]).size;
let str = 'Hello,你好123';
console.log(byteSize(a));
console.log(byteSize(b));
console.log(byteSize(c));
console.log(byteSize(str));
console.log(new Blob([str,c]));